The Mysterious Case of River "Rock Snot"

It’s nicknamed `rock snot’ for pretty obvious reasons, but its source is anything but obvious. The University of Calgary is working with Parks Canada to learn more about this noxious algae’s origins and cause of growth.

Leland Jackson, professor and associate head of grad studies in the Department of Biological Sciences, discovered Didymosphenia geminata, also known as ‘didymo,’ when he was conducting research on land use and its effect on the Red Deer, Oldman and Bow rivers in 2004.
“We just happened to stumble upon rock snot,” Jackson says. While not damaging to humans, rock snot can disrupt river ecosystems. “Bad cases cover the bottoms of rivers like shag carpeting. This alters water flow between the water and sediments and the sediments may not obtain correct oxygen exchange.”

The lack of oxygen in the lower levels of the rivers can affect food and life cycles, including fish reproduction.

There are many unanswered questions about rock snot. “One of the big questions is why didymo may suddenly transform its growth habit, resulting in the bloom conditions capable of altering aquatic food webs and reducing available habitat for fish, invertebrates and plants,” says Barb Johnston, an ecosystem scientist from Waterton Lakes National Park.
Research conducted over the next few months by Parks Canada and the U of C will provide a better understanding of the distribution, abundance and genetic affiliations of didymo. Researchers say it appears to be widespread. Almost every stream sampled from the Red Deer drainage (north of the Bow drainage) to Waterton Lakes National Park has Didymo. It is also an issue in the U.S. in Glacier National Park.

Another question is whether didymo in the mountain parks is a native or an introduced genetic strain. “DNA forensics, our biological version of CSI-Calgary, will allow us to do this,” says Garry Scrimgeour an aquatic ecologist with Parks Canada in Calgary.

“Parks Canada will use information collected in 2009 to develop a program to monitor didymo and to evaluate potential prescriptions to reduce its negative effects on stream health.” There are seven parks involved in this study: Banff, Jasper, Mount Revelstoke, Glacier, Yoho, Kootenay and Waterton Lakes.

Discovering the concrete causes of growth will help to develop counter-measures. “Didymo is wasted energy, it has a low nutrient value,” Jackson says. “It’s taking away space from more beneficial algae that organisms can eat and survive off.”